My immediate goal is to develop one or more experimental systems for studying the stereochemistry of protein to nucleic acid binding by x-ray diffraction methods. Specifically, work already in progress is directed toward: 1) purifying and crystallizing the enzyme methionyl tRNA formyltransferase and/or its complex with met-tRNAF, 2) studying the association behavior of histone proteins isolated under non-denaturing conditions, and using this information to aid in crystallizing specific histone-histone and histone-DNA complexes and 3) measuring the hydration behavior of eukaryotic nucleohistone (chromatin) and correlating this data with x-ray diffraction patterns from chromatin gels and fibres so as to obtain the best possible specimens for more detailed x-ray analysis. Most experimental methods used in this research involve optimizing and scaling up routine preparative procedures to maximize the yield and purity of samples on a large scale, and scaling down the size of crystallization experiments to make the best use of purified material, thereby insuring that sufficiently many trials are attempted to give a high probability for success. Any crystallization experiment can be monitored for microcrystallinity by checking for an x-ray powder diffraction pattern. Hence, favorable conditions can be identified before they become apparent on inspection with a light microscope. Hydration and dehydration curves are to be measured by quantitative gravimetric analysis with a microbalance of chromatin specimens equilibrated at constant relative humidity in a dessicator. X-ray diffraction patterns can be measured rapidly using a focussed, high intensity x-ray beam and a linear wire proportional detector.